In order to simplify the hardware structure of NC system of engraving and milling machine tool, reduce the hardware cost and enhance the expansibility, a design scheme of full software NC system based on PC platform was proposed.The CNC platform of engraving and milling machine tool was built, and the EtherCAT master station based on Linux+Xenomai dual kernel real-time system was built.In Linux domain, CNC system software was developed based on Qt, and modules such as UI interface, logic processing, motion control and functional interface were designed; in the Xenomai domain, the hardware driver was developed based on the real-time function library, the process communication module and the timing driver module were designed, and the timing driver module developed by using the finite state machine was highlighted.The work flow of NC machining was described, and the system performance test and machining experiment were carried out. The results show that the system has strong real-time performance and stable operation, which can meet the requirements of CNC machining of engraving and milling machine tool.